In recent years, an organic light-emitting diode (OLED) has been a popular burgeoning display device product domestically and internationally, because the OLED display device has properties such as self-luminescence, wide visual angles, quick response, high luminous efficiency, wide color gamut, low working voltages, thin thickness, availability in large sizes with flexibility, simple processes and so on, further with potential of low costs.
Conventional packaging techniques of packaging the OLED display device at present include a packaging technique by glass of a glass base or metallic cover, a packaging technique by single or multilayered inorganic thin film, and a thin film packaging technique of alternation of organic compounds and inorganic compounds. The thin film packaging technique is specifically adaptable in some special situations that cannot be achieved by conventional encapsulation, such as packaging flexible organic light-emitting diodes and flexible organic solar cells. A main method of enhancing the thin film packaging technique in the industry is using a drying plate or improving barriers against water and oxygen of the thin film packaging layer to the greatest extent, such as multiple layers of organic/inorganic composite thin films are deposited after production of the display device is completed to prolong the path of water and oxygen spreading in the thin film. However, the technique has inherent limitations. Alternately deposited multiple layers of thin films still have pinholes, and the positions of the pinholes generally are the paths for the vapor to infiltrate, which can cause damage or failure of the device. A thin film with little pinholes is further obtained by atomic layer deposition (ALD) in the industry. The technique can resist water and oxygen, but the vapor can also penetrate to some extent.